diff --git a/bin/update_comparisons.js b/bin/update_comparisons.js
new file mode 100755
index 0000000..cc28e1c
--- /dev/null
+++ b/bin/update_comparisons.js
@@ -0,0 +1,60 @@
+#!/usr/bin/node
+
+const cmp = require('../lib/www/server/lib/comparisons');
+
+
+async function main () {
+	console.log("Retrieving project groups");
+	const groups = await cmp.groups();
+
+	if (!Object.keys(groups??{})?.length) {
+		console.log("No groups found");
+		return 0;
+	}
+
+	console.log(`Found ${groups.length} groups: ${Object.keys(groups).join(", ")}`);
+
+	for (const groupName of Object.keys(groups)) {
+		const projects = groups[groupName];
+
+		console.log(`Fetching saved comparisons for ${groupName}`);
+
+		const comparisons = await cmp.getGroup(groupName);
+
+		// Check if there are any projects that have been modified since last comparison
+		// or if there are any pairs that are no longer part of the group
+
+		const outdated = comparisons.filter( c => {
+			const baseline_tstamp = projects.find( p => p.pid === c.baseline_pid )?.tstamp;
+			const monitor_tstamp = projects.find( p => p.pid === c.monitor_pid )?.tstamp;
+			return (c.tstamp < baseline_tstamp) || (c.tstamp < monitor_tstamp) ||
+				baseline_tstamp == null || monitor_tstamp == null;
+		});
+
+		for (const comparison of outdated) {
+			console.log(`Removing stale comparison: ${comparison.baseline_pid} → ${comparison.monitor_pid}`);
+			await cmp.remove(comparison.baseline_pid, comparison.monitor_pid);
+		}
+
+		if (projects?.length < 2) {
+			console.log(`Group ${groupName} has less than two projects. No comparisons are possible`);
+			continue;
+		}
+
+		// Re-run the comparisons that are not in the database. They may
+		// be missing either beacause they were not there to start with
+		// or because we just removed them due to being stale
+
+		console.log(`Recalculating group ${groupName}`);
+		await cmp.saveGroup(groupName);
+	}
+
+	console.log("Comparisons update done");
+	return 0;
+}
+
+if (require.main === module) {
+	main();
+} else {
+	module.exports = main;
+}